The present application claims priority under 35 USC 119 to Japanese Patent Application Nos. 2001-063222 filed on Mar. 7, 2001 and 2001-063978 filed on Mar. 7, 2001 the entire contents thereof are hereby incorporated by reference.
The present invention relates to a shock absorbing structure for vehicles having a riding space for an occupant. The shock absorbing member projects from the vehicle body and is capable of absorbing an impact by crushing the shock absorbing member.
A shock absorbing structure for a vehicle is described in xe2x80x9cVehicle Frame Having a Footboard Portionxe2x80x9d which is disclosed in Japanese Patent Laid-Open No. 67374/1998.
The aforementioned technology comprises a deforming element disposed above a front wheel and forwardly of the main frame pipe, so that when the impact load is exerted from the front of the vehicle, the impact load is received at the deforming element to reduce the impact.
However, since the vehicle frame is provided with the aforementioned footboard portion comprises the deforming element (hereinafter referred to as xe2x80x9cshock absorbing memberxe2x80x9d) is disposed above the front wheel and forwardly of the main frame pipe, there may be the case where it is difficult to provide a shock absorbing member having a sufficient size for absorbing the impact load. Especially, since the general two-wheel vehicle or the cab-over-engine trucks in which the entire or almost all of the portion of the motor is located under the driver""s compartment have a construction without a front nose, it is difficult to dispose the shock absorbing member at the front portion of the vehicle within the region of the vehicle length.
Even in vehicles wherein the disposition of the shock absorbing member at a front portion of the vehicle within the region of the length of the vehicle is difficult, in the case where an impact force is exerted for example, it is still desirable to have the impact load efficiently absorbed.
FIGS. 10(a) and 10(b) are explanatory drawings illustrating the action of a shock absorbing structure for motorcycles according to background art. As shown in FIG. 10(a), a fork 1103 is attached on the head pipe 1102 provided on the body frame 1101 of the motorcycle 1100. A front wheel 1104 is mounted on the fork 1103. A deforming element (hereinafter, referred to as xe2x80x9cshock absorbing memberxe2x80x9d) 1105 is mounted on the front end of the vehicle frame 1101 so that the sock absorbing member 1105 is disposed above the front wheel 1104.
The shock absorbing member 1105 comprises a foamed material 1108 in the hollow portion 1107 of the frame body 1106.
In FIG. 10(a), when the motorcycle 1100 comes into a collision with an obstruction 1110, the front end portion 1105a of the shock absorbing member 1105 comes into collision with the obstruction 1110, and the impact force F1 due to collision acts on the front end portion 1108a of the foamed material 1108 as shown by the arrow.
In FIG. 10(b), the impact force acts on the front end portion 1108a of the foamed material 1108 to crush the front end portion 1108a of the foamed material 1108. In this way, the impact force F1 is reduced by having the front end portion 1108a of the foamed material 1108 crushed, so that the resultant reduced impact force is transmitted to the frame.
In order to reduce the impact force F1 when the motorcycle 1100 comes into a collision with an obstruction 1110, it is necessary to determine the crush amount of the shock absorbing member 1105 to be a large value to some extent.
However, if the crush amount of the shock absorbing member 1105 is too large, the motorcycle 1100 may move as shown by the arrow and the rear portion of the vehicle body may bounce upwardly into the air, which may result in pitching (that is a lurching forward or backward of the vehicle body).
Therefore, in order to obtain two effects such as preferably reducing the impact force F1 and preventing the occurrence of pitching, it is necessary to strictly determine the crush amount of the shock absorbing member 1105. Therefore, it is desirable to commercialize a shock absorbing member 1105 in which the crush amount of the shock absorbing member 1105 can easily be adjusted.
Accordingly, an object of the present invention is to provide a technology to efficiently absorb an impact load, when it is exerted on a vehicle, and to minimize the damage to the riding space of the occupant.
In order to achieve the object described above, in an a vehicle having a riding space for an occupant, the shock absorbing structure for the vehicle according to the present invention comprises a bumper member extending substantially along the length of the vehicle under or by the sides of the riding space for receiving an external force heading from the front to the occupant, and a shock absorbing member connected at the rear ends of the bumper member.
The bumper member extends along the length of the vehicle for receiving an external force heading towards the occupant and the shock absorbing member is connected at the rear ends of the bumper member to absorb the impact load.
In other words, by providing the bumper member extending along the length of the vehicle under or by the sides of the riding space and connecting the shock absorbing member for absorbing the impact load at the rear end of the bumper member, when an impact load is exerted thereon, the impact load can be efficiently absorbed even in the vehicles in which arrangement of the shock absorbing member at the front portion thereof is difficult within the range of the length of the vehicle.
The shock absorbing structure for vehicles according to the present invention is characterized in that when the crushing amount of the shock absorbing member is referred to as the effective crushing length of the shock absorbing member, the effective crushing length is the length from the front end of the vehicle body to the front end of the riding space.
The total amount of movement of the bumper member for maintaining the riding space is preferably the length from the front end of the vehicle body to the front end of the riding space. Therefore, by determining the effective crushing length of the shock absorbing member to be the length from the front end of the vehicle to the front end of the riding space, the total amount of movement allowed for maintaining the riding space is given to the bumper member.
Accordingly, it is an object of the present invention to provide a shock absorbing structure for two-wheel vehicle in which the crush amount of the shock absorbing structure can easily be determined so as to satisfy two requirements for significantly reducing the impact force and preventing occurrence of pitching.
In order to achieve the aforementioned object, the present invention provides a shock absorbing structure for two-wheel vehicle for absorbing the impact by having a shock absorbing body projecting from the vehicle body that is crushed. The shock absorbing body comprises an upper shock absorbing member disposed on the upper side, and a lower shock absorbing member disposed below the upper shock absorbing member. The upper and lower shock absorbing members are formed of two types of members having different crushing features.
The shock absorbing body is constructed of the upper shock absorbing member and the lower shock absorbing member. The upper and lower shock absorbing members are constructed of two types of members having different crushing features. Since the shock absorbing body is formed by combining two types of members having different crushing features as described above, the crushing extent of the shock absorbing body can desirably be determined corresponding to the two-wheel vehicle.
According to the present invention, the lower shock absorbing member is characterized by being easily deformable by a low-load in comparison with the upper shock absorbing member.
By making the lower shock absorbing member easily deformable with a low-load, the impact can be sufficiently absorbed. In addition, since the upper shock absorbing member can prevent the shock absorbing body from being crushed too much, the rear portion of the vehicle body of the two-vehicle is prevented from bouncing upwardly into the air upon collision.
According to the present invention a structure is provided wherein the two members are constructed of foamed resin of the same material but different in crushing feature due to the difference in density.
By forming the two members of foamed resin of the same material in different densities, the crushing features of two members may be differentiated. The crushing features of the two members can be differentiated relatively easily because it is achieved only by making the density of the foamed resin different.
In addition, foamed resin is a material that is available relatively easily, and the cost thereof is relatively low. Therefore, the cost of the upper and lower shock absorbing members can be reduced.
Furthermore, since foamed resin is a material that can be processed relatively easily, it can be formed into a desired shape relatively easily.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.